GCG and pancreatic insulinoma: In a 1993 publication by Mitrakou A et al., they demonstrated that there was generally a decreased counter-regulatory hormone level (plasma catecholamines, glucagon, growth hormone, and cortisol) in insulinoma patients when they conducted stepped hypoglycaemic-clamp studies in 6 insulinoma patients when compared to 14 normal subjects (matched for age, weight and sex).